Infectious conjunctivitis

INTRODUCTION — 

Conjunctivitis (ie, inflammation of the conjunctiva) is categorized as infectious or noninfectious (allergic, toxic, or nonspecific). Infectious conjunctivitis can be further categorized into bacterial or viral etiologies.

This topic will focus on the clinical manifestations, diagnosis, and treatment of infectious conjunctivitis in adults and children. Undifferentiated red eye and noninfectious causes of conjunctivitis are discussed elsewhere.

●(See "The red eye: Evaluation and management".)

●(See "Allergic conjunctivitis: Clinical manifestations and diagnosis".)

●(See "Toxic conjunctivitis".)

●(See "Plasminogen deficiency", section on 'Ligneous conjunctivitis'.)

ANATOMY — 

The conjunctiva is the mucous membrane that lines the inside surface of the lids and covers the surface of the globe up to the limbus (the junction of the sclera and the cornea). The portion covering the globe is the "bulbar conjunctiva," and the portion lining the lids is the "tarsal conjunctiva" (figure 1).

The conjunctiva is generally transparent. When inflamed, it appears pink or red because the fine blood vessels become prominent (termed “injection”) and can be seen upon close examination. In contrast, extravasated blood from subconjunctival hemorrhage appears as a confluent red, flat or slightly elevated, area under the conjunctiva.

INITIAL APPROACH

Indications for urgent ophthalmology referral — The most common types of bacterial and viral conjunctivitis are typically benign and self-limiting conditions. However, certain features may suggest more serious types of infectious conjunctivitis and should prompt urgent ophthalmology referral (or an emergency care facility with ophthalmology support).

Alarm symptoms and signs — Features that are not typical of common bacterial or viral conjunctivitis include:

●Decreased visual acuity

●Profuse mucopurulent discharge

●Inability to spontaneously open the eye

●Atypical time course, including rapidly progressive/worsening symptoms over hours; or chronic conjunctivitis lasting weeks to months

●Conjunctivitis in a newborn

These characteristics suggest less common sight-threatening infectious conjunctivitis types, including hyperacute bacterial conjunctivitis, epidemic keratoconjunctivitis, or chlamydial conjunctivitis, all of which require ophthalmology evaluation. (See 'Hyperacute bacterial (gonococcal) conjunctivitis' below and 'Epidemic keratoconjunctivitis' below and 'Chlamydial conjunctivitis' below.)

Other features, such as severe headache with nausea, photophobia, severe foreign body sensation, decreased extraocular motility, pain with extraocular movement, proptosis, ciliary flush, corneal opacity, or fixed pupil, may suggest an alternate diagnosis altogether, such as acute angle-closure glaucoma, uveitis, orbital cellulitis, or infectious keratitis (infection of the cornea).

These conditions are also sight-threatening and require urgent ophthalmology evaluation. A broad overview of the red eye and these alternate conditions are discussed elsewhere:

●(See "The red eye: Evaluation and management".)

●(See "Angle-closure glaucoma".)

●(See "Uveitis: Etiology, clinical manifestations, and diagnosis" and "Uveitis: Treatment".)

●(See "Orbital cellulitis".)

●(See "Complications of contact lenses", section on 'Infectious keratitis'.)

●(See "Herpes simplex keratitis".)

Note that while photophobia and severe foreign body sensation are generally alarm signs, they may also be present in corneal abrasion, a condition that can be initially treated in the primary care or emergency care setting, with referral to ophthalmology if symptoms persist. (See "Corneal abrasions and corneal foreign bodies: Clinical manifestations and diagnosis" and "Corneal abrasions and corneal foreign bodies: Management".)

Conjunctivitis-focused history and examination — Patients may refer to their red or pink eye as "conjunctivitis," but clinicians should review the history, symptoms, and signs to confirm the diagnosis of conjunctivitis and assess the type (eg, infectious versus allergic).  

History — The following information should be determined:

●Demographic information, including whether the patient is an adult or child, contact with individuals with similar symptoms, and time of year.

●Systemic symptoms such as fever, sore throat, lymphadenopathy, and ear pain. High fever, severe sore throat, and conjunctivitis in a child may suggest pharyngoconjunctival fever (see 'Pharyngoconjunctival fever' below). In both adults and children, a history of chronic, recurring, or seasonal symptoms and eye itching are suggestive of allergic conjunctivitis, which is discussed in detail separately. (See "Allergic conjunctivitis: Clinical manifestations and diagnosis".)  

●Ocular symptoms, including change in vision, pain or foreign body sensation, redness, and discharge, and the acuity of onset. History of mucopurulent or watery discharge should be elicited. Decreased vision is not typical of common infectious conjunctivitis, and its presence may be suggestive of another etiology or subtypes of infectious conjunctivitis warranting ophthalmologic evaluation and management.

●Contact lens use or trauma, which should prompt investigation for etiologies other than conjunctivitis, including evaluation for keratitis. Management of contact lens users is different from that of non-contact lens users. (See 'Contact lens wearers' below.)

Examination — The following examination elements should be evaluated:

●Visual acuity, which should be normal (or unchanged) in common infectious conjunctivitis.

●Presence of, and characteristics of ocular discharge, including watery or mucopurulent.  

●Pattern of conjunctival redness (injection). In conjunctivitis, the injection is diffuse, involving the bulbar (globe) conjunctiva for 360 degrees as well as the palpebral (tarsal) conjunctiva (the mucous membrane on the inner surface of the lids). If conjunctival injection is localized (picture 1) rather than diffuse, another diagnosis such as foreign body, pterygium, or episcleritis should be considered (see "Pterygium" and "Episcleritis"). If the tarsal conjunctiva is spared, keratitis, iritis, and angle-closure glaucoma should be considered. These serious conditions cause a red eye with 360 degree involvement of the bulbar conjunctiva, often in a ciliary flush pattern, but without tarsal conjunctival involvement. (See "The red eye: Evaluation and management".)

●Presence of corneal opacity, which is not consistent with common infectious conjunctivitis (picture 2).

●Presence of non-ocular findings including preauricular lymphadenopathy and pharyngitis, which are often associated with viral conjunctivitis. Presence of otitis media is associated with bacterial conjunctivitis.  

Non-contact lens wearers

Making a clinical diagnosis of viral or bacterial conjunctivitis — The diagnosis of common viral versus bacterial conjunctivitis is made clinically, based on the constellation of demographics, seasonality of infection, and multiple features.

Some features are more common with each type of infection, though none in isolation are diagnostic.

●Features more commonly associated with viral etiology – Clinical features that are associated with higher likelihood of common viral conjunctivitis include [1-3] (see 'Common viral conjunctivitis' below):

•Adult patient

•Summer months (in the United States [2])

•Contact with another person with red eye  

•Watery discharge

•Preauricular lymphadenopathy

•Pharyngitis  

•Outbreak settings

●Features more commonly associated with bacterial etiology – Clinical features that are associated with higher likelihood of bacterial conjunctivitis include [1,3] (see 'Common bacterial conjunctivitis' below):

•Pediatric patient

•Non-summer months (fall, winter, early spring)

•Mucopurulent discharge

•Presence of acute otitis media

●Features common to both viral and bacterial conjunctivitis

•Unilateral or bilateral involvement  

•Discomfort, which is highly subjective, varies among patients, and could be described as grittiness, burning, foreign body sensation, or pain

•Varying degrees of lid swelling and conjunctival chemosis (edema)

It is important to note that no single clinical feature reliably distinguishes between bacterial and viral conjunctivitis, as there is overlap of symptoms. For example, in a meta-analysis including 32 studies, 21 percent of patients with viral conjunctivitis had mucopurulent discharge and 26 percent of patients with bacterial conjunctivitis had watery discharge [3]. Thus, using single clinical features alone to differentiate the etiology can result in high rates of misdiagnosis. In studies that evaluated the diagnostic accuracy of single clinical symptoms to differentiate etiology, misdiagnosis rates ranged from 40 to 75 percent [4].

As common viral and bacterial conjunctivitis are clinical diagnoses, many times there is no definitive diagnosis or specific treatment. However, the conditions are typically self-limiting, and the patient improves without specific therapy.  

Limited role for testing — Microbiologic testing, including polymerase chain reaction (PCR), cultures or stains, is usually unnecessary for the initial diagnosis and therapy of common conjunctivitis. Ophthalmologists typically do not perform microbiologic testing, even when they are referred patients who have not responded to initial therapy. Swabbing for culture, stains, and direct antibody or PCR testing is typically reserved only for atypical or chronic cases that fail to improve or respond to therapy.  

There are some exceptions:  

●Suspected hyperacute bacterial conjunctivitis – Patients with signs and symptoms of hyperacute bacterial conjunctivitis including rapidly progressive symptoms over hours, profuse purulent discharge, and decreased visual acuity should have nucleic acid amplification testing (NAAT), or Giemsa and Gram stains in some settings, to identify Neisseria gonorrhoeae. (See 'Hyperacute bacterial (gonococcal) conjunctivitis' below.)

●Suspected chlamydial conjunctivitis – Chlamydia causes several forms of conjunctivitis depending on chlamydia serotype and patient population. Testing is indicated in suspected cases. (See 'Chlamydial conjunctivitis' below.)

●Suspected adenoviral conjunctivitis – In outbreak cases or high-risk work environments such as health systems or food services, where there is high concern for adenovirus conjunctivitis, a rapid point-of-care antigen-based (10-minute) test for adenoviral conjunctivitis in adult patients may reduce unnecessary antibiotic use and potential costs [5,6]. Among adults, the sensitivity of the test has significant variability, ranging from 39 to 92 percent, while the specificity ranges from 92 to 100 percent compared with PCR [5,7-9]. Adequate sampling is likely critical to achieving higher test sensitivity. When there is high concern for adenovirus conjunctivitis and test results will influence decisions regarding return to work, school, or other settings in which outbreaks are to be avoided, a negative antigen test can be followed by a PCR test, though availability may be limited.

We do not routinely use antigen-based tests in children as these have not been validated in this population. Furthermore, sampling in children is more difficult and adenovirus conjunctivitis is less common compared with adults, which reduces the positive predictive value of the test.

Initial management — Therapy should be directed at the most likely etiology of conjunctivitis suggested by the history, physical examination, and other clinical features (table 1). Our approach is presented in the algorithm (algorithm 1).

In addition, patients should be managed according to the following general principles.

Supportive care — We routinely recommend supportive care given the potential benefits and minimal risk of harm. This includes warm or cool compresses, lubricating eye drops (eg, artificial tears), and/or lubricating ointments, which can be purchased over the counter. There are a wide variety of products on the market with various formulations, none proven superior for symptomatic relief (table 2).

Lubricant drops can be used as often as hourly for one to two days with no side effects. Lubricant ointment provides longer-lasting relief but blurs vision; thus, many patients use the ointment only at bedtime. It may be worthwhile to switch brands if a patient finds one brand of drop or ointment irritating since each preparation contains different active ingredients, vehicles, and preservatives. Preservative-free preparations are more expensive and are necessary only when frequency of use is greater than four times daily on a chronic basis (as in the case of severe dry eye or allergy in highly allergic patients). Over-the-counter antihistamine/decongestant drops or antihistamine/mast cells stabilizer drops may be helpful, particularly if itching is a prominent symptom, but should be discontinued if symptoms worsen.

Selecting candidates for antibiotic therapy — We prescribe antibiotics to all patients with suspected gonorrheal or chlamydial conjunctivitis. (See 'Hyperacute bacterial (gonococcal) conjunctivitis' below and 'Chlamydial conjunctivitis' below.)

For most patients with suspected common bacterial conjunctivitis, we suggest supportive management rather than antibiotic therapy. We typically reserve antibiotics only for contact lens wearers, patients with immunocompromise or concurrent medical issues (who may require additional evaluation or treatment), extenuating circumstances such as inability to follow-up, or conjunctivitis that is not following a typical course of resolution. Some clinicians also might consider antibiotics in patients who value a possibly shortened symptom duration more than the cost, inconvenience, and possible side effects of eye drops. Additionally, we only prescribe antibiotics after a thorough examination. (See 'Specific treatment' below and 'Contact lens wearers' below.)

The rationale is that in cases of common bacterial conjunctivitis, antibiotics confer no or only modest benefit in earlier resolution of symptoms [10-12]. Furthermore, antibiotic use has not been demonstrated to reduce transmission of bacterial conjunctivitis [13,14]. In cases of allergic and viral conjunctivitis, antibiotics confer no benefit. (See 'Rationale for restrictive antibiotic use' below.)

The decision to prescribe an antibiotic should be based on clinical necessity rather than exclusion policies. The American Academy of Pediatrics recommends against requiring antibiotic use prior to return to childcare or school. A prior quality improvement program that included a standardized return to childcare and school note referencing the American Academy of Pediatrics and Centers for Disease Control and Prevention recommendations resulted in a significant decrease in antibiotic prescribing and did not result in increased subsequent clinic or urgent care visits or return visits to obtain an antibiotic prescription [15].

However, providers are often pressured to routinely prescribe antibiotics for conjunctivitis. For example, patients often call all cases of red or pink eye "conjunctivitis" and may presume that all cases are bacterial and require antibiotics. Parents or other caregivers may request antibiotics because many childcare centers and schools require that students with conjunctivitis receive 24 hours of topical therapy before returning to school. Patients also sometimes request to be treated without being examined, and nurse triage lines may have protocols for routine prescription of antibiotics [16,17]. Such protocols result in high use of antibiotics [15,16,18], which may pose a risk of adverse drug events and increase antibiotic resistance among ocular pathogens [19,20]. (See 'Preventing transmission and returning to work, school, and childcare' below.)

No role for steroid use — Ophthalmic glucocorticoids (either alone or in combination steroid/antibiotic drops) have no role in the management of acute conjunctivitis by primary care clinicians [21]. Glucocorticoids can cause sight-threatening complications (eg, corneal scarring, melting, and perforation) when used inappropriately. Chronic ophthalmic glucocorticoid treatments can also cause cataract and glaucoma [22,23].

Ophthalmologists may prescribe topical glucocorticoids in certain cases of ocular allergy, viral keratitis, and chronic blepharitis. Use in these conditions should be supervised by an ophthalmologist as discussed in separate topic reviews. (See "Allergic conjunctivitis: Management", section on 'Corticosteroids' and "Atopic keratoconjunctivitis", section on 'Topical corticosteroids' and "Vernal keratoconjunctivitis", section on 'Topical corticosteroids' and "Blepharitis", section on 'Topical glucocorticoids'.)

Contact lens wearers

●Making a clinical diagnosis – In general, we apply the same principles of evaluation and diagnosis in contact lens wearers as non-contact lens wearers. (See 'Conjunctivitis-focused history and examination' above and 'Making a clinical diagnosis of viral or bacterial conjunctivitis' above.)

However, the diagnosis of infectious conjunctivitis should be made carefully in contact lens wearers. Contact lens wearers, especially those with extended-wear lenses, have a high risk of pseudomonal ulcerative keratitis, which can lead to ocular perforation within 24 hours if not recognized and treated appropriately. Pseudomonas may form biofilms on soft contact lenses, which predisposes users to infection, particularly with prolonged use and improper hygiene. P. aeruginosa is the most common bacteria associated with bacterial keratitis in contact lens wearers (>50 percent of isolates), followed by Serratia, Staphylococcus, and Streptococcus species [24].

Bacterial keratitis is typically associated with decreased visual acuity, photophobia, severe foreign body sensation, and inability to spontaneously open the eye or keep it open. If a corneal opacity is visible with a penlight (picture 2), keratitis is present and emergent same-day evaluation by an ophthalmologist is required.

Contact lens wearers are also subject to acute conjunctivitis or keratitis from overwear and secondary chronic conjunctivitis that may require a change in contact lens fit, lens type, or lens hygiene, or suppression of hypersensitivity. Neither of these are associated with a focal corneal opacity.

●Management – Keratitis should be ruled out prior to diagnosis and treatment of conjunctivitis. If there is any suspicion of keratitis or any atypical features in a contact lens wearer, ophthalmology referral is required (see "The red eye: Evaluation and management", section on 'Infectious keratitis'). Typically, decision to treat and choice of antibiotic is made empirically, without obtaining cultures.  

In contact lens wearers with suspected or possible bacterial conjunctivitis, we recommend topical antibiotics due to the increased risk of keratitis and/or infection with gram-negative organisms. We have a much lower threshold to use antibiotics for suspected or possible bacterial conjunctivitis in contact lens wearers than non-contact lens wearers. Fluoroquinolones are the preferred agent (table 2) due to the high incidence of Pseudomonas infection. (See 'Specific treatment' below.)

In contact lens wearers in whom viral conjunctivitis is very likely and there is no suspicion of keratitis, we recommend supportive care, as in non-contact lens users. (See 'Supportive care' above.).

Patients should stop using their contact lenses until complete clinical improvement is achieved. In bacterial conjunctivitis, this is when the eye is white and has no discharge for 24 hours after the completion of antibiotic therapy. In viral conjunctivitis, this is when the eye is white with no discharge. The lens case should be discarded and the lenses subjected to overnight disinfection or replaced if disposable.

Chronic conjunctivitis in a contact lens wearer is best addressed by an experienced optometrist or an ophthalmologist.

SPECIFIC TYPES OF INFECTIOUS CONJUNCTIVITIS

Bacterial conjunctivitis

Common bacterial conjunctivitis

Epidemiology — Bacterial conjunctivitis is the most common type of infectious conjunctivitis in children, accounting for 50 to 75 percent of cases, but an infrequent cause of conjunctivitis in adults, accounting for 10 to 30 percent of cases [1,3,10,25].  

Microbiology — The conjunctiva is not sterile, even in people without conjunctivitis. In children, normal conjunctival flora includes Staphylococcus epidermidis, Streptococcus, and Staphylococcus aureus [26]. In adults, normal conjunctival flora includes coagulase-negative staphylococci (predominantly S. epidermis), S. aureus, Propionibacterium, Corynebacterium, Pseudomonas, and Haemophilus influenzae [27,28].

The microorganisms implicated in infectious conjunctivitis are different between pediatric and adult populations [29-31]. In children with bacterial conjunctivitis, H. influenzae is the predominant bacteria implicated [10,25,32]. In a multicenter case-control study that included 195 cases and 194 controls, H. influenzae was the only bacteria associated with conjunctivitis, identified in 62 percent of cases versus 29 percent of controls (adjusted odds ratio [OR] 4.59, 95% CI 2.86-7.37). Other bacteria such as S. pneumoniae, Moraxella catarrhalis, S. aureus (rare) may also be identified from the conjunctiva of children with acute conjunctivitis, however, these bacteria are identified with similar frequency among children without conjunctivitis.

In adults with bacterial conjunctivitis, S. aureus is the most commonly identified bacteria (26 percent) followed by other Staphylococcus species [32]. Coliform species, as well as H. influenzae, M. catarrhalis, and S. pneumoniae are also identified. Pseudomonas prevalence has also been found to increase from primary to tertiary care settings.

Clinical features — Mucopurulent discharge and acute otitis media are associated with higher likelihood of bacterial conjunctivitis [3]. Discharge may be thick and globular; yellow, white, or green; and located at the lid margins and corners of the eye. It continues throughout the day and may reappear within minutes of wiping the lids (picture 3). Other features that may be present in bacterial conjunctivitis, though not associated with higher likelihood ratios, include the eye being “stuck shut” in the morning and bilateral eye involvement.  

Diagnosis — Bacterial conjunctivitis is a clinical diagnosis based on the constellation of demographics, seasonality of infection, and multiple clinical features. For example, conjunctivitis in children, in non-summer months, with concomitant otitis media and mucopurulent discharge is most likely bacterial. Resolution of symptoms in five to seven days with or without therapy supports the diagnosis.

Specific treatment — We typically reserve antibiotics only for contact lens wearers, immunocompromised patients (who may require additional evaluation or treatment), or extenuating circumstances such as inability to follow-up, conjunctivitis that is not following a typical course of resolution, or concurrent medical issues. (See 'Selecting candidates for antibiotic therapy' above.)

Antibiotic treatment is also required for cases of gonococcal or chlamydial conjunctivitis. (See 'Hyperacute bacterial (gonococcal) conjunctivitis' below and 'Chlamydial conjunctivitis' below.)

Treatment options for common acute bacterial conjunctivitis are presented in the table (table 2). In contact lens wearers, we use ophthalmic fluoroquinolones. In non-contact lens wearers, our preferred antibiotic is ophthalmic erythromycin ointment or trimethoprim-polymyxin drops. We treat for a duration of five days. There is no evidence to favor either ointment versus drops. For many children and infants, we utilize drops for easier administration and decreased blurring of vision compared with ointment.

Alternative antibiotics are included in the table (table 2):

●Bacitracin-polymyxin B ointment (limited by cost and patient sensitivity) and bacitracin ointment (limited by cost).

●Azithromycin is approved in the United States as an ophthalmic solution for bacterial conjunctivitis in patients one year of age and older. It is dosed less frequently than other ophthalmic solutions (one drop twice daily for two days, then one drop daily for five days) but is considerably more expensive than erythromycin or sulfacetamide, and its availability raises a concern about promoting the emergence of organisms resistant to azithromycin, which could limit its use for other infections [33].

●Fluoroquinolones are not first-line therapy for bacterial conjunctivitis in non-contact lens wearers because of concerns regarding emerging resistance and cost. We do use fluoroquinolones in contact lens wearers due to the high incidence of Pseudomonas infection.

●Chloramphenicol drops are a generally inexpensive and well-tolerated option used widely around the world for the treatment of bacterial conjunctivitis. However, topical use of chloramphenicol has been associated with the very rare but catastrophic complications of bone marrow hypoplasia, aplastic anemia, and death and is not marketed or used in the United States for the treatment of ocular infections [34]. Abbreviated drug information is available. (See "Chloramphenicol (ophthalmic): International drug information (concise)".)

●Sulfacetamide ophthalmic drops are not a first-line option because of the potential for rare but serious allergic events.

●Aminoglycoside drops and ointments are poor choices since they are toxic to the corneal epithelium and can cause a reactive keratoconjunctivitis after several days of use.

Rationale for restrictive antibiotic use — We do not routinely prescribe antibiotics because bacterial conjunctivitis is self-limited in most cases, and antibiotics confer either no or modest benefit in shortening the clinical course [1,10-12,35]. Our approach is supported by the following lines of evidence:  

●Limited effect on time to clinical cure – The evidence regarding benefit in shortening clinical course of symptoms is mixed.

•Adult and children – In a 2023 Cochrane meta-analysis of adult and pediatric patients that included five clinical trials (1474 participants), antibiotics likely improved clinical cure between days 4 to 9 compared with placebo (68.2 versus 55.5 percent, RR 1.26, 95% CI 1.09-1.46) [12].

•Children – In a randomized trial that included 326 children randomly assigned to chloramphenicol or placebo, clinical cure at day 7 was similar in both groups (86 versus 83 percent) [10]. However, in another study, post-hoc subgroup analysis of 815 pediatric participants randomly assigned to besifloxacin or placebo, clinical cure rates was higher for children who received the antibiotic (88 versus 73 percent) [36]. In contrast, a three-arm clinical trial that included 88 children randomly assigned to moxifloxacin, no treatment, or placebo, showed clinical cure rates were similar for the moxifloxacin and placebo groups (3.8 versus 4.0 days) [11]. Children prescribed moxifloxacin did have a shorter duration of symptoms than those with no treatment (3.8 versus 5.7 days), though it is unclear if this difference is from efficacy, placebo effect, or washout effect, with removal of bacteria from the eye via irrigation by topical solution.

●Risk of adverse effects – Adverse drug events occur in up to 8 percent of patients who use antibiotics [10,25,37]. However, there is little evidence of serious systemic side effects in patients receiving ocular antibiotics [12].

●No reduction in complications – Complications from common conjunctivitis are rare and antibiotics do not reduce the risk of these complications.

●No reduction in transmission – Antibiotics do not reduce the transmission of conjunctivitis among children. In two studies that evaluated transmission rates of conjunctivitis, transmission rates did not differ between children who did and did not use an ophthalmic antibiotic [13,14]. (See 'Selecting candidates for antibiotic therapy' above.)

●Risk of developing antibiotic resistance – Use of antibiotics, particularly fluoroquinolones, accelerates the development of antibiotic resistance among ocular pathogens.

Outcome — As discussed above, most patients do well with conservative therapy and topical antibiotics, when indicated. We provide patients with a contingency plan to return to care if symptoms worsen or do not improve with treatment. (See 'Management of patients with persistent symptoms' below.)

Less common bacterial conjunctivitis

Hyperacute bacterial (gonococcal) conjunctivitis — Neisseria species, particularly N. gonorrhoeae, can cause a hyperacute bacterial conjunctivitis that is severe and sight-threatening in adults, though it mainly affects neonates (picture 4) [38]. Hyperacute bacterial conjunctivitis requires immediate ophthalmologic referral.

In adults, the organism is usually transmitted from the genitalia to the hands and then to the eyes. Concurrent urogenital symptoms are typically present. In neonates, infection is transmitted during birth. Onset of symptoms is typically between two to five days after birth. Concurrent findings may also include pharyngitis, arthritis, or gonococcemia.

This type of conjunctivitis is characterized by a strikingly profuse, purulent discharge, which can present within 12 hours of inoculation in adults [39]. Symptoms are rapidly progressive and include severe redness, irritation, and tenderness to palpation. There is typically marked chemosis and lid swelling. Patients may also have tender preauricular adenopathy. Left untreated, keratitis occurs in 15 to 40 percent of cases and can rapidly progress to perforation, causing severe loss of vision [40].

The conjunctiva should be swabbed and the specimen sent for immediate Gram stain to identify gram-negative diplococci. Nucleic acid amplification testing (NAAT) can also be used for diagnosis of gonococcal conjunctivitis [41].

Systemic therapy is required and discussed elsewhere. (See "Treatment of uncomplicated gonorrhea (Neisseria gonorrhoeae infection) in adults and adolescents", section on 'Conjunctivitis'.)

Chlamydial conjunctivitis

●Trachoma – Trachoma is a chronic infectious disease caused by Chlamydia trachomatis serotypes A-C and is the leading cause of preventable blindness worldwide. Conjunctivitis is the major clinical manifestation of active trachoma, a chronic keratoconjunctivitis caused by recurrent infection with C. trachomatis. This disorder is largely limited to endemic areas in less resource-abundant countries and is discussed separately. Active trachoma is most common in children and is typically symptomatic with redness, discomfort, light sensitivity, and mucopurulent discharge. The clinical manifestations and treatment of trachoma are discussed in detail elsewhere. (See "Trachoma".)

●Adult inclusion conjunctivitis – Adult inclusion conjunctivitis is a chronic, indolent conjunctivitis. It is a sexually transmitted infection (STI) caused by C. trachomatis serotypes D-K. It is estimated to occur in 5 to 36 percent of sexually active adolescents and young adults presenting with chronic conjunctivitis [42,43], though the prevalence is likely to change given the epidemiologic increase in overall rates of chlamydia infections. Concurrent urogenital infection occurs in up to 80 percent of patients and is often asymptomatic [44,45].  

The eye infection presents as a unilateral, or sometimes bilateral, follicular conjunctivitis of weeks to months duration that does not respond to topical antibiotic therapy. There can be an associated keratitis. This diagnosis should be considered in chronic cases of conjunctivitis among populations at risk for STI.

NAAT of specimens collected from the affected lower eye lid is the gold standard for diagnosis given its high sensitivity and specificity. In settings where NAAT is not available, direct fluorescent antibody (DFA) testing or enzyme immunoassay (EIA) testing can be utilized. Culture and Giemsa staining can be utilized in resource-limited settings but have considerably lower sensitivity [46].

Antibiotic treatment for adult inclusion conjunctivitis is the same as systemic therapy and is discussed elsewhere. (See "Treatment of Chlamydia trachomatis infection in adults and adolescents".)  

●Infectious conjunctivitis in the neonate – Conjunctivitis in the neonate is characterized by variable eye discharge, eyelid swelling, and conjunctival injection and chemosis. In cases of chlamydial infection, the onset of symptoms is 5 five to 14 days after birth. Infectious conjunctivitis in the neonate is discussed separately. (See "Gonococcal infection in the newborn" and "Chlamydia trachomatis infections in newborns and young infants".)

Viral conjunctivitis

Common viral conjunctivitis

Epidemiology — Viral conjunctivitis is the most common cause of infectious conjunctivitis in the adult population and is most prevalent in summer [1,3,47].

Microbiology — Adenovirus is the most common cause of viral conjunctivitis and is estimated to account for 70 to 90 percent of infectious conjunctivitis cases in adults. There are multiple adenovirus serotypes, which cause unique clinical syndromes. Common viral conjunctivitis, also known as “simple follicular conjunctivitis,” is caused by multiple adenoviral serotypes [4].  

Coxsackievirus, enterovirus, and echoviruses also cause conjunctivitis in adults and children. Among children, picornavirus-associated conjunctivitis occurs with similar frequency to adenovirus conjunctivitis (6 to 7 percent in some studies), and has been associated with large outbreaks of conjunctivitis in childcare, work, and school settings [10,25]. Numerous other viruses also cause conjunctivitis [48]. For example, among patients with COVID-19, up to 11 percent experience ocular manifestations, most commonly conjunctivitis [49]. During a 2024 outbreak of highly pathogenic avian influenzae A (H5N1), conjunctivitis was present in all nine patients testing positive for influenza A(H5) [50]. (See "Avian influenza: Clinical manifestations and diagnosis", section on 'Signs and symptoms'.)

Clinical features — Clinical features associated with a higher likelihood of viral conjunctivitis include contact with another person with red eye, preauricular lymphadenopathy, and pharyngitis [3]. Conjunctivitis can also be part of the prodrome or presentation of other viral upper respiratory tract infections.

Other features of viral conjunctivitis include profuse tearing or a watery or mucoserous discharge [3]. When mucoid discharge is present, it is typically only observed if the lower lid is pulled down or the corner of the eye is closely examined. Other symptoms include burning, sandy, or gritty sensation in the eye (picture 5). The tarsal conjunctiva may have a follicular or "bumpy" appearance (picture 6), and the preauricular node may be enlarged and tender.

Diagnosis — The diagnosis of viral conjunctivitis is clinical and should be made based on the constellation of demographics, seasonality of infection, and multiple clinical features. For example, infectious conjunctivitis that occurs in adults, in outbreak settings, associated with pharyngitis or preauricular lymphadenopathy, and/or in the summer, without mucopurulent discharge, is most likely to be viral in etiology.

Specific treatment — No topical or systemic antiviral agent is used for the treatment of routine viral conjunctivitis and antibiotics play no role in the management. We routinely recommend only supportive care given the potential benefits and minimal risk of harm. (See 'Supportive care' above.)

Clinicians must be wary of trying one or more agents in patients with viral conjunctivitis who are expecting drugs to "cure" their symptoms. Patients should be counseled about the natural history of the disease (see 'Outcome' below) and that the use of any topical agent (antibiotics or antihistamine/decongestant) might result in irritation and toxicity, which also can cause redness and discharge. Patient education is often more effective than prolonged or additional therapies for patients who experience improvement but incomplete resolution of symptoms after a few days.

We advise patients who choose to use an over-the-counter topical antihistamine/decongestant (naphazoline-pheniramine) or antihistamine/mast cell stabilizers (ketotifen, olopatadine, and others) to discontinue use if their symptoms worsen. Although some patients find relief in switching from one to another, there is little evidence that one is superior for symptoms.

Outcome — Common viral conjunctivitis is usually a self-limited process, paralleling that of the common cold. Symptoms may get worse for the first three to five days, but typically improve within five to seven days with very gradual resolution over the following one to two weeks, for a total course of two to three weeks. Patients may have morning crusting for two weeks after the initial symptoms, although the daytime redness, irritation, and tearing should be improved.

Less common viral conjunctivitis

Pharyngoconjunctival fever — Pharyngoconjunctival fever (PCF) typically occurs in children and is frequently caused by adenovirus serotype 3, though other serotypes including 2, 4, 7, and 14 may be implicated. Children typically present with severe sore throat, high fever, and conjunctivitis. Most symptoms improve within one week and resolve within two weeks. PCF is more common in the summer months and may be associated with outbreaks at summer camps and swimming pools [51,52].

Epidemic keratoconjunctivitis — Epidemic keratoconjunctivitis (EKC) is a particularly fulminant type of viral conjunctivitis. Keratitis typically develops a few days after the initial conjunctivitis. EKC is typically caused by adenovirus types 8, 19, and 37 [53]. However, there is clinical variation; the same viral strain that causes EKC in one patient may cause common viral conjunctivitis in another, probably due to differences in host immune factors. EKC is highly contagious via direct contact with the patient and their secretions or with contaminated objects and surfaces [54].

The corneal and conjunctival epithelium are both involved. In addition to the typical symptoms of viral conjunctivitis, the patient may describe a foreign body sensation. The foreign body sensation is sufficiently severe to preclude opening the eyes spontaneously, and the infiltrates typically degrade acuity by two or three lines to the 20/40 range. Multiple corneal infiltrates are sometimes visible with a penlight (though easily seen at the slit lamp).

Keratitis is potentially vision-threatening, and patients should be referred to an ophthalmologist to confirm the diagnosis and to decide whether a course of ophthalmic glucocorticoids is warranted.

Acute hemorrhagic conjunctivitis — Acute hemorrhagic conjunctivitis (AHC) is most frequently associated with coxsackie A24 and enterovirus 70. Other viruses including coxsackie B1 and B2, echoviruses 7 and 11, and adenovirus are infrequent causes of AHC. AHC has a short incubation period of one to two days and may occur in large outbreaks. Clinical features include intensely red eyes, chemosis, discharge, significant discomfort with a foreign body feeling in the eye, and subconjunctival hemorrhages giving the eye an intense blood-shot appearance [55-58]. Systemic symptoms are typically uncommon or mild. Eye discomfort typically resolves within one week, but it may take up to three weeks for the eye to appear normal. Most cases are uncomplicated, but some outbreak reports have indicated potentially high rates of secondary bacterial keratitis and decreased visual acuity.

Other viral infections associated with conjunctivitis — Conjunctivitis may accompany herpes simplex virus (HSV) keratitis, acute varicella zoster (chickenpox), or herpes zoster ophthalmicus (V1 shingles), though the conjunctival process itself is typically self-limited. Conjunctivitis may also be a manifestation of ocular mpox, as well as more serious conditions including keratitis and corneal ulceration, that require prompt and aggressive treatment [59]. Specific anti-viral therapy may be indicated for other ocular manifestations in these conditions.

●(See "Herpes simplex keratitis", section on 'Management'.)

●(See "Treatment of varicella (chickenpox) infection".)

●(See "Treatment and prevention of mpox (formerly monkeypox)", section on 'Ocular infections'.)

Anti-viral therapies have not demonstrated efficacy in reducing morbidity associated with varicella conjunctivitis. Some clinicians may opt to use topical antibiotics in cases of varicella conjunctivitis where corneal involvement is suspected, in addition to ophthalmology consultation.

DIFFERENTIAL DIAGNOSIS

Non-infectious conjunctivitis

Allergic conjunctivitis — Allergic conjunctivitis is caused by airborne allergens contacting the eye. It typically presents with prominent itching, which is the cardinal symptom of allergy, as well as bilateral redness and watery discharge (picture 7). Itching typically distinguishes allergic from a viral etiology, which is more typically described as grittiness, burning, or irritation. Patients often have a history of atopy, seasonal allergy, specific allergy (eg, to cats), or other allergic symptoms (eg, nasal congestion, sneezing, wheezing). Allergic conjunctivitis is described in detail elsewhere. (See "Allergic conjunctivitis: Clinical manifestations and diagnosis".)

The clinical findings are the same as those seen in viral conjunctivitis. Both cause diffuse injection with a bumpy or follicular appearance to the tarsal conjunctiva (picture 6).  

Toxic conjunctivitis — Toxic conjunctivitis (also called toxic keratoconjunctivitis) is a chronic inflammation of the surface of the eye due to an offending agent, usually a preservative or medication. Symptoms typically develop over weeks to months of ocular medication use and are most frequently reported in those using glaucoma drops. Toxic conjunctivitis is discussed in a separate topic. (See "Toxic conjunctivitis".)

Noninfectious, noninflammatory conjunctivitis — Patients can develop a red eye and discharge that is not related to either an infectious or inflammatory process. The discharge is more likely mucus than purulent. Usually the cause is a transient mechanical or chemical insult. All of these conditions generally improve spontaneously within 24 hours.

●Patients with dry eye may report chronic or intermittent redness or discharge and may interpret these symptoms as being related to an infectious cause.

●Patients whose eyes are irrigated after a chemical splash may have redness and discharge; this is often related to the mechanical irritation of irrigation rather than superinfection.

●Patients with an ocular foreign body that was spontaneously expelled may have redness and discharge for 12 to 24 hours.

●Patients with ligneous conjunctivitis are discussed separately. (See "Plasminogen deficiency", section on 'Ligneous conjunctivitis'.)

Chronic or persistent causes of red eye — Other diagnoses to consider in patients with persistent symptoms include dry eye (see "Dry eye disease"), pterygium (see "Pterygium"), and blepharoconjunctivitis (see "Blepharitis"), and adult inclusion conjunctivitis. (See 'Chlamydial conjunctivitis' above and "The red eye: Evaluation and management".)

MANAGEMENT OF PATIENTS WITH PERSISTENT SYMPTOMS — 

Patients with bacterial conjunctivitis usually improve and/or show response to treatment within 72 hours by showing a decrease in discharge, redness, and irritation and have clinical resolution within seven days.

Patients with viral conjunctivitis usually improve within five to seven days and have resolution of symptoms in two to three weeks [10,11,25].

Patients who do not respond or have worsening symptoms should follow up with their primary care provider and be referred to an ophthalmologist.

PREVENTING TRANSMISSION AND RETURNING TO WORK, SCHOOL, AND CHILDCARE

●Household infection prevention – Patients and caregivers should exercise good hand hygiene, avoid touching the eyes, and avoid sharing towels, linens, and cosmetics until symptoms have resolved. Routine infection prevention measures including disinfecting hard surfaces can reduce the spread of infection.

●Exclusion from childcare or school – Children, who predominantly have bacterial etiologies of infectious conjunctivitis, should not be routinely excluded from childcare or school unless systemic symptoms, such as fever, are present that would otherwise warrant exclusion. Though state policies vary, the American Academy of Pediatrics and the Centers for Disease Control and Prevention do not recommend routine exclusion from school or childcare for conjunctivitis.

In two studies that evaluated secondary attack rates of conjunctivitis among children, rates ranged from 7 to 12 percent [13,14]. For comparison, secondary attack rates of other common childhood infections for which children are not routinely excluded, such as rhinovirus, are 25 to 70 percent [60]. In a prior cost-effectiveness analysis, unnecessary exclusion of children from childcare and school and unnecessary antibiotic use resulted in considerable health care utilization, costs, and reduced pediatric quality of life [61].

●No role for antibiotics in transmission reduction – Antibiotics do not reduce the risk of transmission, as discussed above. (See 'Specific treatment' above.)

●Suspected adenoviral conjunctivitis – Because adenoviral conjunctivitis is highly contagious and may be associated with epidemic keratoconjunctivitis, we typically recommend that these patients stay home from work, school, childcare, and sports for a minimum of seven days and until symptoms have improved, in accordance with the American Academy of Ophthalmology preferred practice pattern [35]. Staying home from work is particularly relevant for patients who work in a health care setting or in food services.

Patients are most contagious for the first week of infection but may shed virus for up to 21 days. Some protocols recommend that patients stay home for 10 to 14 days, or until all symptoms have resolved. Given the high personal and/or parental burden associated with exclusion from the workforce, school, or childcare, we recommend diagnostic testing to confirm the diagnosis, prior to prolonged exclusion. Protocols for adenovirus testing and exclusion in health care settings are available and have demonstrated economic advantages by avoiding unnecessary exclusion and reducing transmission [62].

INFORMATION FOR PATIENTS — 

UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Conjunctivitis (pink eye) (The Basics)")

●Beyond the Basics topics (see "Patient education: Conjunctivitis (pink eye) (Beyond the Basics)" and "Patient education: Allergic conjunctivitis (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Overview – Conjunctivitis (ie, inflammation of the conjunctiva) is categorized as infectious (bacterial or viral) or noninfectious (allergic, toxic, or nonspecific). In children, most infectious conjunctivitis is bacterial, whereas in adults most infectious conjunctivitis is viral.

Undifferentiated red eye and noninfectious causes of conjunctivitis are discussed elsewhere.

•(See "The red eye: Evaluation and management".)

•(See "Allergic conjunctivitis: Clinical manifestations and diagnosis".)

•(See "Toxic conjunctivitis".)

●Indications for urgent ophthalmology referral – In patients in whom a diagnosis of common infectious conjunctivitis is being considered, alarm features (eg, decreased visual acuity, profuse mucopurulent discharge, inability to open the eye) could be signs of an aggressive form of conjunctivitis, or alternative conditions such as keratitis, uveitis, or angle closure glaucoma. These alarm features should prompt urgent ophthalmology referral. (See 'Initial approach' above and 'Alarm symptoms and signs' above.)

●Conjunctivitis-focused evaluation – Demographic information, season of presentation, history of contact lens use, and presence of systemic and ocular symptoms and signs should be determined. If the patient wears contact lenses, heightened vigilance for keratitis and consideration of ophthalmology referral is appropriate. (See 'Conjunctivitis-focused history and examination' above and 'Contact lens wearers' above.)

●Making a presumptive clinical diagnosis

•Viral versus bacterial – A clinical diagnosis of common viral versus bacterial conjunctivitis is made using multiple features with emphasis on demographics, seasonality of symptoms, and clinical features associated with higher likelihood of viral or bacterial etiologies. Distinguishing based on single features is not reliable as there is clinical overlap.

-Viral conjunctivitis is more common among adults and occurs more often in the summer. Features associated with higher likelihood of viral conjunctivitis include contact with another person with red eye, watery discharge, preauricular lymphadenopathy, pharyngitis, and outbreak settings.

-Bacterial conjunctivitis is more common among children and occurs more often during respiratory season (fall, winter, early spring). Features associated with higher likelihood of bacterial conjunctivitis include mucopurulent discharge and presence of acute otitis media.

Characteristics that are associated with higher likelihood of respective conditions are presented in the table and graphic (table 1).

•Features that should not be used in distinguishing etiology – Laterality of ocular symptoms, eyes being stuck closed in the morning, and single clinical features should not be used in distinguishing between the etiologies of infectious conjunctivitis.

Common viral and bacterial conjunctivitis are clinical diagnoses, and there is often no definitive diagnosis or specific treatment. However, the conditions are typically self-limiting and improvement occurs without specific therapy.

•Differential diagnosis – All etiologies of conjunctivitis can cause discharge, redness, and discomfort. Allergic conjunctivitis should be considered in patients with pruritus, which is not common in infectious conjunctivitis. Additionally, allergic conjunctivitis may be chronic, recurring, or seasonal. (See "Allergic conjunctivitis: Clinical manifestations and diagnosis".)

●Limited role for laboratory testing – Diagnostic testing for conjunctivitis is not routinely performed, except in cases of suspected hyperacute bacterial (gonococcal) conjunctivitis or chlamydial conjunctivitis. Occasionally, we will also test in cases of suspected adenoviral conjunctivitis in high-risk environments such as health systems or food services. (See 'Limited role for testing' above.)

●Supportive care – Supportive care is helpful in any patient with infectious conjunctivitis and may include warm or cool compresses, lubricating eye drops (eg, artificial tears), and/or lubricating ointments. (See 'Supportive care' above.)

●Selecting candidates for antibiotic therapy – For most patients (non-contact lens wearers) with presumed bacterial conjunctivitis, we suggest against antibiotic therapy (Grade 2C) (algorithm 1).

We selectively prescribe antibiotics for presumed bacterial conjunctivitis as follows (after a thorough examination) (see 'Selecting candidates for antibiotic therapy' above):

•All patients with suspected gonorrheal or chlamydial conjunctivitis require systemic antibiotics and may need ophthalmology evaluation. Treatment of these patients is reviewed separately.

-(See "Treatment of uncomplicated gonorrhea (Neisseria gonorrhoeae infection) in adults and adolescents", section on 'Conjunctivitis'.)

-(See "Trachoma", section on 'Treatment' and "Chlamydia trachomatis infections in newborns and young infants".)

-(See "Chlamydia trachomatis infections in newborns and young infants".)

-(See "Treatment of Chlamydia trachomatis infection in adults and adolescents".)

•For patients with common bacterial conjunctivitis:

-Contact lens wearers – For contact lens wearers, we recommend antibiotic therapy over supportive management alone (Grade 1C). We suggest ophthalmic ofloxacin drops, ciprofloxacin drops, or ciprofloxacin ointment (Grade 2C) (table 2). Topical fluoroquinolones are preferred due to the high incidence of Pseudomonas. Patients should temporarily discontinue lens use and discard the used lenses and lens case. Contact lens use can be resumed when symptoms resolve. (See 'Contact lens wearers' above.)

-Non-contact lens wearers – For patients who are immunocompromised, have concurrent medical issues, or extenuating circumstances, we suggest antibiotic therapy over supportive management alone (Grade 2C). We suggest ophthalmic erythromycin ointment or trimethoprim-polymyxin drops (Grade 2C) (table 2). For many children and infants, we utilize drops for easier administration and decreased blurring of vision compared with ointment. Ointment may be preferred in those with difficulty administering eye drops but may blur the vision. (See 'Specific treatment' above.)

●Management of patients with persistent symptoms – Patients with presumed viral or bacterial conjunctivitis who do not start improving within a few days, or have worsening symptoms, should follow up with their primary care physician and be referred to an ophthalmologist. (See 'Management of patients with persistent symptoms' above.)

●Transmission – Transmission is limited by avoiding direct contact with secretions or contaminated objects (eg, makeup, contact lenses). (See 'Preventing transmission and returning to work, school, and childcare' above.)

•Children predominantly have bacterial conjunctivitis and may continue to attend childcare and school unless other systemic symptoms, such as fever, are present that would warrant exclusion. Antibiotics do not reduce transmission and are not required for return to childcare or school.

•Adults predominantly have viral conjunctivitis and may remain infectious for a variable period related to the underlying viral syndrome. For adenoviral conjunctivitis, patients should refrain from attending work, school, or childcare for a minimum of seven days or until symptoms are improved. Given the economic burden associated with missing work, school, or childcare, diagnostic testing for adenovirus may be helpful to justify prolonged exclusion from work, school, or childcare.